Japanese Patent Application Laid-open publication No. 2003-301942 discloses an automatic transmission apparatus for a vehicle. With the disclosed transmission apparatus, a driver needs less force than otherwise for operating the shift lever thanks to a motor driven in response to the value detected by a torque sensor provided to the shift lever.
This type of automatic transmission apparatus for a vehicle begins the power assist control on the shift lever when the detected value of the torque sensor exceeds a certain threshold value. On the other hand, the automatic transmission apparatus stops the power assist control when the detected value of the torque sensor is equal to, or less than, the threshold value, or when the shift lever moves to a certain predetermined shift position. The detected value of the torque sensor becomes zero, which is below the above-mentioned threshold value, when the driver's hand is released from the shift lever. As a result, the automatic transmission apparatus stops the power assist control.
In this type of automatic transmission apparatus for a vehicle, the torque sensor detects the load on the shift lever at the side of the motor. In addition, a position gate is provided to restrict the movement of the shift lever. A press on the operation button on the shift lever releases the restriction by the position gate, and allows the driver to operate the shift lever.